1. Field of the Invention
The present invention relates to a process for producing an integrated and assimilated structure of synthetic corundum single-crystals which is used as an ornamental article, a scientific appliance, an industrial instrument or the like and which is made by putting a plurality of single crystal plates of synthetic corundum one on another and chemically bonding them.
2. Description of the Prior Art
Synthetic corundums such as sapphire have been conventionally used for a spectroscopical container (cell) for optical transmission samples because of the excellent optical wavelength transmission characteristics and their excellent resistances to chemicals and recently, they are being also used for a superconductive container because of their larger thermal conductivities.
One example of a process for producing such a cell is shown in FIG. 15. In this process, as shown in FIG. 15(a), is recessed plate 32 made of teflon is interposed as a packing between two corundum window plates 30 and 31 into a state shown in FIG. 15(b), and bolts and nuts are inserted into through-holes 33 penetrating the corundum window plates 30 and 31 and the recessed plate 32 and tightened to form the cell.
In such a method, however, if the bolts are too tight, schlierens and strains may be produced, or even if optical wavelength transmission characteristics available for a spectroscopic container or cell are satisfactory, the respect of a resistance to chemicals is unsatisfactory. More specifically, a solution may be gradually penetrated between the plate and the teflon packing, but such method had to be used from necessity. On the other hand, with the super-conductive cell, there is a difference in coefficient of thermal expansion between the corundum window plate and the teflon packing due to their resistance to freezing, pressure and heat and hence, not only this cell is not fit for use, but also, it is very dangerous.
In addition, in making a thin super-conductive film, a substrate must be fit for use in a normal CVD process even at temperatures more than 900.degree. C., and less than 268.9.degree. C.
A microminiature material capable of measuring a ultra-amount super-precisely and super-correctly and having characteristics of resistance to freezing, heat, pressure and chemicals is only a single crystal of synthetic corundum (e.g., sapphire) ranking in hardness next to diamond having the highest hardness on the earth. Except for the requirement of the above resistances, however, if a material is amorphous, such materials, even if they are homogeneous, can be affixed to each other because they have no anisotropy. On the other hand, it is impossible to affix single crystals having an anisotropy such as synthetic corundum in view of their crystallographic structures. On the consideration that such affixing is contrary to solid physics and out of the bounds of possibility, the experiments and studies therefor have been not made, and even similar examples cannot be found.
In the regard to the aforesaid optical polishing, the polished face will now be described. The polished face is a flat face of a wavelength order and has a flatness accuracy .lambda./8 or less of red ray wavelength (.lambda.=6328.ANG.) as measured by HeNe laser interference flatness-measuring device.
In the conventional boring method using a ultrasonic machine, it is technically and technologically very difficult to bore a rectangular hole in a rectangular prism and further to polish the inner surface of the rectangular hole, and hence, it requires a great deal of skill to do so. If a rectangular through hole is made by boring, however, it is possible to polish the inner surface of the through hole. If the boring operation is discontinued in the middle to provide a rectangular hole rather than a rectangular through hole, it is impossible to polish the inner surface thereof. Therefore, the conventional cell of synthetic corundum is a non-bottomed flow cell and hence, in a case bottom is necessary, a plug must be mounted. This is the case of a cylinder having a rectangular through hole to the end, rather than the case of a bottomed container.
In addition, if a rectnagulr hole is bored to provide a container, the inner surface of that rectangular hole cannot be polished with optically high accuracy.
As described above, it is impossible to produce an integrated optically measuring container from single crystals of synthetic corundum through a boring method.